Gravure printing is a process known for quite some time. The basic concepts of gravure printing are known in ancient Italy and China. In China, it is said to have evolved from 100 AD, where printing plates were prepared by hand using engraving tools. In the 16th century with the invention of etching using chemicals, scratching of images as a resistant coating on the surface of metal printing plate was known. With the advent of photography in the late 19th century, the challenge of reproducing images that are near to real world posed the printing industry. This was when gravure was able to duplicate the photographic films by using gelatin, which hardened when exposed to light. The unhardened areas were washed away and etched using acid. These paved way for gravure printing techniques that are widely used today.
Gravure printing is vastly used in various industries including that of packaging. By using this technique many packaging products are made. Further, plastic tubes form an integral part of the packaging industry as they are used to enhance the shelf-life of packaged goods and create a unique product identity. Laminated Tubes are used for packaging in various sectors like oral care, food, cosmetics, pharmaceuticals, and also for other industrial applications. The oral care industry contributes to 70% of production of laminated tubes. The laminated tubes thus made are of two types, viz. Aluminium Barrier Laminates (ABL) tubes that have an aluminum foil barrier, which provides superior light, air and moisture barrier along with reduced flavor absorption. The material density offers a more durable tube and allows for additional dispensing of the products contents. Pastes, ointments, cream and gels typically dentifrice, over-the-counter and pharmaceutical products fare well in Aluminium Barrier Laminates (ABL) tube packaging. The second type of laminated tubes is Plastic Barrier Laminates (PBL) tubes that possess structures that are a good option for packaging with a need to maintain its form and shape. It presents a more cosmetic look and is environmental friendly. Special barriers can be provided such as Ethylene Vinyl Alcohol Polymer (EVOH), Nylon to offer a strong chemical resistance. Standard material is offered in white or natural (clear) but specialty custom colors can also be developed.
U.S. Pat. No. 6,041,929 discloses a film bag with hidden indicia formed in the film bag laminate, which is not viewed from outside the package. GB Patent 2,338,679 discloses a substrate for security documents such as banknotes, cheques, passports, etc. U.S. Pat. No. 5,443,915 discloses an oriented polyolefinic laminated film which has a core, a TiO2 containing white partially cold seal receptive polyolefinic skin layer on one side of the core, and a vacuum metalized surface on the other side of the core. US Patent application 2006/01519993 discloses a laminated security documents or tokens and process for manufacturing the same.
Plastic barrier layer (PBL) laminate tubes are also made of the polymers, but the barrier layer is made of a polymeric material, Ethyl Vinyl alcohol (EVOH) or Nylon. The Plastic barrier layer (PBL) laminated tubes are widely used in applications requiring attractive packaging such as for cosmetic products, good resilience (ability of tubes to return to their original shape after squeezing), and attractive visual and tactile effects. The Plastic barrier layer (PBL) laminated tubes are emerging as an alternative to aluminum foil based tubes.
The structure of the Plastic barrier layer (PBL) laminated tube known in the state-of-the-art comprises a polyethylene (PE) white layer as an outer layer. It has two layers of polyethylene (PE) encompassing a central layer of ethylene vinyl alcohol (EVOH), which acts as a barrier between the polyethylene (PE) layers. Finally it has an outer layer facing the product of polyethylene (PE). The laminates, which can be tailor-made, are either made transparent/clear or opaque or colored. Generally, the master batch consists of one form of laminates, i.e. transparent, opaque or colored.